1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for managing access to satellite-based networks, and particularly to determining whether specific geopolitical areas and/or individuals are allowed access to the satellite-based network.
2. Background and Objects of the Present Invention
Cellular telecommunications is one of the fastest growing and most demanding telecommunications applications ever. Today it represents a large and continuously increasing percentage of all new telephone subscriptions around the world. A standardization group, Global System for Mobile Communication (GSM), was established in 1982 to formulate the specifications for mobile cellular radio systems.
With reference now to FIG. 1 of the drawings, there is illustrated a GSM Public Land Mobile Network (PLMN), such as cellular network 10, which in turn is composed of a plurality of areas 12, each with a Mobile Services Center (MSC) 14 and an integrated Visitor Location Register (VLR) 16 therein. The MSC/VLR areas 12, in turn, include a plurality of Location Areas (LA) 18, which are defined as that part of a given MSC/VLR area 12 in which a mobile station (MS) 20 may move freely without having to send update location information to the MSC/VLR area 12 that controls the LA 18. Each Location Area 12 is divided into a number of cells 22. Mobile Station (MS) 20 is the physical equipment, e.g., a car phone or other portable phone, used by mobile subscribers to communicate with the cellular network 10, each other, and users outside the subscribed network, both wireline and wireless. The MS also includes a Subscriber Identity Module (SIM) 13, which provides storage of subscriber related information, such as the International Mobile Subscriber Identity (IMSI) 15, which uniquely identifies a subscriber.
The MSC 14 is in communication with at least one Base Station Controller (BSC) 23, which, in turn, is in contact with at least one Base Transceiver Station (BTS) 24. The BTS is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the geographical part of the cell 22 for which it is responsible. It should be understood that the BSC 23 may be connected to several base transceiver stations 24, and may be implemented as a stand-alone node or integrated with the MSC 14. In either event, the BSC 23 and BTS 24 components, as a whole, are generally referred to as a Base Station System (BSS) 25.
With further reference to FIG. 1, the PLMN Service Area or cellular network 10 includes a Home Location Register (HLR) 26, which is a database maintaining all subscriber information, e.g., user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, and other administrative information. The HLR 26 may be co-located with a given MSC 14, integrated with the MSC 14, or alternatively can service multiple MSCs 14, the latter of which is illustrated in FIG. 1.
The VLR 16 is a database containing information about all of the Mobile Stations 20 currently located within the MSC/VLR area 12. If a MS 20 roams into a new MSC/VLR area 12, the VLR 16 connected to that MSC 14 will request data about that Mobile Station 20 from the HLR database 26 (simultaneously informing the HLR 26 about the current location of the MS 20). Accordingly, if the user of the MS 20 then wants to make a call, the local VLR 16 will have the requisite identification information without having to reinterrogate the HLR 26. In the aforedescribed manner, the VLR and HLR databases 16 and 26, respectively, contain various subscriber information associated with a given MS 20.
It should be understood that the aforementioned system 10, illustrated in FIG. 1, is a terrestrially-based system. In addition to the terrestrially-based systems, there are a number of satellite systems, which work together with the terrestrially-based systems to provide cellular telecommunications to a wider network of subscribers. One such satellite system, which will be implemented in the near future, is the ICO Global Communications network.
The ICO network is a group of mid-range satellites that cover most of the earth. In the ICO network, as shown in FIG. 2 of the drawings, a system of satellites 200 in multiple, non-geosynchronous orbits are used to provide communication between Mobile Stations (MS) 210 and the land-based part of the network, called the Satellite Acces,s Node (SAN) 220. The SAN 220 consists of equipment for communicating with the satellites 200 and through the satellites 200 to the mobile stations 210. The antennae and satellite tracking part of the system is the Radio Frequency Terminal (RFT) subsystem 230, which also provides for the connection of the communication path to the satellite 200. Connected to the RFT 230 is a Land Earth Station (LES) 240, which is similar in function to a combination of the Base Transceiver Station (BTS) 24 and the Base Station Controller (BSC) 23 for GSM based systems, as illustrated in FIG. 1. Land Earth Stations (LESs) coordinate communications to and from the satellite 200 and the respective local systems servicing the area, e.g., other cellular systems 10 attached to the satellite-based system 205.
Within the ICO network, a function exists in the LES 240 for calculating what xe2x80x9cService Areaxe2x80x9d 250 a system access is being requested from. This Service Area 250 can in turn be mapped onto a country or state for the purpose of disabling ciphering or routing emergency calls, e.g., 911 calls, to the nearest emergency center in order to meet regulatory requirements and to provide the correct language set.
A Terrestrial Network Manager (TNM) 280 performs some of the functions of the BSC 23 of FIG. 1 as well as additional functions unique to satellite based systems, such as multi-SAN paging and routing of registration messages to the correct MSC/VLR 290. One key function of the TNM 280 is the ability to map paging requests (which are broadcast messages to the MS 210, using the IMSI 15, to instruct the MS 210 to respond, e.g., by sending a CM SERVICE REQUEST message), using X,Y coordinates, onto the resources needed to execute the paging. In other words, based on the coordinates, the TNM 280 can determine which LES 240 is the most suitable for paging. In addition, the TNM 280 consults a database 260, which includes a set of tables, to decide which Channel Managers, contained within the LES 240, and satellite beams should be used for paging.
The ICO network currently provides service across most of the earth, including the north and south poles using 12-20 SANs, each of which can, under various circumstances and depending on configuration and satellite visibility, provide service to almost anywhere in the world. However, such ubiquity of service carries a price. In order to operate within a jurisdiction, the service provider (ICO network) must obtain a license from that jurisdiction, which involves conforming to various requirements, such as providing the ability to handle emergency calls. Different geopolitical areas have different licensing requirements, and not all licensing requirements are likely to be met at the same time.
Each satellite 200 within the ICO network has the ability to provide service to a large area, which can include numerous distinct countries or other jurisdictions, e.g., states, each with separate licensing agreements. With reference now to FIG. 3 of the drawings, a difficult situation arises when a satellite 300, which covers countries A 310, B 320, C 330, D 340, and E 350, receives an operating license in Country A 300, B 310 and D 330, but not in Country C 320.
The situation becomes even more complicated if, in addition to the foregoing, a restricted operating license is granted in Country E 350, in which only certain subscribers within Country E 350 are allowed access to the system from only certain areas, such as Country E 350 and Country E""s 350 allies. In other words, in this situation, access is denied completely for some xe2x80x9cregulatory areasxe2x80x9d, e.g., Country D 330, and denied for certain groups of subscribers or subscribers attempting to place calls from unauthorized areas for other regulatory areas, e.g., Country E 350.
Due to the method in which mobility management is handled in the ICO network, such as Service Area mapping without location area Location Updating, it is not presently possible to meet these requirements for mobile terminating calls. The ICO network does not have location areas, and therefore, Location Updating restriction checking is not presently possible.
It is therefore one object of the invention to provide means for storing, within a satellite-based network, the geopolitical areas and individuals allowed access to the network.
It is a further object of the invention to provide means for determining, based on the information stored within the network, whether the called party is allowed access to the network.
It is still a further object of the invention to provide means for determining, based on the information stored within the network, whether the calling party is allowed access to the network.
The present invention is directed to telecommunications systems and methods for managing access to a satellite-based network by including within, for example, the tables that the TNM consults, information regarding areas with no allowed service and areas with restricted service. Once the location and the International Mobility Subscriber Identity (IMSI) of the calling and/or called party are determined, the tables can be consulted to determine whether the calling and/or called party should be excluded from the satellite/beam selection. This requires the IMSI to always be sent in the page request. Advantageously, the systems and methods of the present invention are not dependent on accurate location information being stored in the MSC/VLR.